New Geforce GT 640(GDDR5) preventing computer from starting up

[MWCarlton]

Hi, I just got a New Nvidia Geforce GT 640 1GB GDDR5 card(from EVGA), tried installing it in my HP H8-1230( Manufacturer Specs ) to replace the GT 620 it comes with. This system is on Windows7 64bit, and I did not replace any drivers before installing the new card.

When I got everything reconnected and tried to boot it back up, it froze on the very first screen. some kind of manufacturer screen, blue with the HP logo and the computer model number, and a bit of text, press Esc to select boot mode. Normally that screen flashes by, but it froze there.
I tried rebooting and hitting F8 to get to a boot menu, and all I got was a black screen with system specs instead of the Blue screen, but just as frozen. I tried that a few times with no luck, except once a "select boot mode" text appeared in the bottom right corner, but I was still frozen.

My question is, could a problem like this be caused by the card drivers? Or is this more likely to be some rare incompatibility or just a faulty card? The 640 I have supposedly has the same wattage draw as my older 620, from reading the manufacturer spec page, so I have been ruling out power supply issues.
I haven't seen any threads discussing issues like this where a card will prevent a computer from booting even in Safemode, so I'm thoroughly confused.
Any help would be very much appreciated. This 640 is, I think, the best card I can run on my 300W PSU, and I don't really want to deal with upgrading it yet.

 

[MWCarlton]

Hmm. Thank you for the reply but-

Nvidia GeForce GT 620:
Maximum Graphics Card Power (W) 49W
Minimum System Power Requirement (W) 300W

^ that is currently in and working

Nvidia GeForce GT 640 1024MB GDDR5:
Maximum Graphics Card Power (W) 49W
Minimum System Power Requirement (W) 300W
(this is the manufacturer specs)

^ that is what I want to work, but my system fails to boot when it's in.
You're right that on the sale page for the EVGA card, it says it requires 350W and minimum 20 amps on the +12 volt rail, but it doesn't say anything about the actual maximum wattage pull. Now, I know that the total watt power supply is just a guess based on average system power draw, so I assumed that since the two cards have the same power requirements on Nvidia's site that the EVGA card would use the same. is it actually using more power or is their guess just aimed at higher draw systems? If it is then trading out to an Asus or Gigabyte card would solve this problem.

Also, is this sort of issue (total inability to boot, even in safe mode) common from low power issues? I thought it was more likely to just clock-down the card, and reduce performance? Which is making me fearful of trying this card again.

So, assuming I don't want to trade out my PSU, should I try another Geforce GT 640 from Asus or Gigabyte or someone, that is not Superclocked, or is this some kind of bizarre issue and I should just try and find a lower end card?
Any help would be very much appreciated.

 

[MWCarlton]

ahhh, okay, it's like you're not reading my posts.... the Card I have in RIGHT NOW < Right now, as we speak. I am posting this post, right now, using this card in my H8-1230. Okay? The card I have in now is the Nvidia Geforce GT 620, and it's manufacturer specs list it's maximum power consumption at 49W. So we've established that my PSU can, at the very least boot up with a card that has 49W max power consumption, right? I would guess so, at least. so taking that into account, we would guess that a another graphics card, which also has a max power consumption of 49W would also work. Or at least I have. sooooo, lets assume my power supply can do a 49W card...because it is -right now- literally as I type.
There's the possibility that the EVGA card I have has more power draw than what is listed on the manufacturer specs page, the answer to that question would really help me.
My computer's motherboard is the Angelica2, and after some looking around the Nvidia 640 series is not listed as compatible on pc-specs.com. Is that a sign that it will cause crazy incompatibility issues, or could it just not be listed there? the answer to that question would really help me.

I'm sorry if I come off terse.

 

[RMCEEDY]

i have exactly the same issue with my HP PC, but with the Gainward version of the gt 640 gddr5. Been looking for a solution for weeks, but none have worked. One I saw was to flash (or update) the bios, which is risky but I'm tempted to do to get the card to work